The present invention relates to 1-N-phenylamino-1H-imidazole derivatives as aromatase inhibitors and to pharmaceutical compositions containing them.
Aromatase is the physiological enzyme responsible for the specific conversion of androgens such as androstenedione or testosterone, into estrogens such as estrone and estradiol, respectively (Simpson E R et al., Endocrine Reviews, 1994, 15: 342-355). Inhibition of aromatase iso, therefore, a strategy of choice to interfere with normal or pathological estrogen-induced or estrogen-dependent biological processes such as female sexual differentiation, ovulation, implantation, pregnancy, breast and endometrial cell proliferation as well as regulation of spermatogenesis or prostate cell proliferation in male or of non-reproductive functions such as bone formation or immune T cell and cytokine balance (Simpson E R et al., Recent Progress in Hormone Research, 1997, 52: 185-213 and the whole issues of Endocrine Related Cancer (1999, volume 6, nxc2x0 2) and Breast Cancer Research Treatment (1998, volume 49, supplement nxc2x0 1)).
A large number of azole derivatives are known as antifungal agents. Some imidazole or triazole derivatives have already been described as inhibitors of the enzyme aromatase. Generally, the imidazolyl or the triazolyl group is associated with aromatic rings as found in letrozole (EP-A-236 940; Lamb H M and Adkins J C, Drugs, 1998, 56: 1125-1140): 
or anastrozole (EP-A-296 749; Wiseman L R and Adkins J C, Drugs Aging, 1998, 13: 321-332): 
Imidazoles or triazoles linked via a methylene group to a benzotriazole are described in EP-A-293 978: 
Diterbutyl phenols having a N-amino-imidazole moiety in the para position are described in U.S. Pat. No. 4,908,363 and are presented as having inflammation-inhibiting and oedema-inhibiting properties: 
More recently, M. OKADA et al. (Chem. Pharm. Bull., 44 (10), 1996, 1871-1879) described a series of [4-(bromophenylmethyl)-4-(cyanophenyl)amino]-azoles and their azine analogs: 
It has now been found that imidazole derivatives which invariably contain a 1-[N-phenylamino]group demonstrate an unexpectedly high potency to inhibit aromatase.
Accordingly, one object of this invention is to provide 1-[N-phenylamino]imidazole derivatives which are potent aromatase inhibitors.
Another object of this invention is to provide a pharmaceutical composition containing, as active ingredient, a 1-[N-phenylamino]imidazole derivative as depicted below or a pharmaceutically acceptable acid addition salt thereof.
A further object of this invention is to provide the use of a 1-[N-phenylamino]imidazole derivative in the manufacture of a medicament intended for treating or preventing various diseases and for managing reproductive functions in women, in men as well as in female and male wild or domestic animals.
The 1-[N-phenylamino]imidazole derivatives of this invention are represented by the following general formula (I): 
and acid addition salts, solvates and stereoisomeric forms thereof, wherein:
R1 and R2 are each independently hydrogen, a (C1-C6)alkyl or a (C3-C8)cycloalkyl;
n=0, 1, 2;
R3, R4, R5 and R6 are each independently hydrogen, or a (C1-C6)alkyl, halogen, cyano, (C1-C6)alkoxy, trifluoromethyl, (C1-C6)alkylthio, (C1-C6)alkylsulfonyl, sulfonamido, acyl, (C1-C6)alkoxycarbonyl, or carboxamido group;
R3 and R6 together with the phenyl ring bearing them can also form a benzofurane or a N-methylbenzotriazole.
In the description and claims, the term xe2x80x9c(C1-C6)alkylxe2x80x9d is understood as meaning a linear or branched hydrocarbon chain having 1 to 6 carbon atoms. A (C1-C6)alkyl radical is for example a methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, isopentyl or hexyl radical.
The term xe2x80x9chalogenxe2x80x9d is understood as meaning a chlorine, bromine, iodine or fluorine atom.
The term xe2x80x9c(C3-C8)cycloalkylxe2x80x9d is understood as meaning a saturated monocyclic hydrocarbon having 3 to 8 carbon atoms. A (C3-C8)cycloalkyl radical is for example a cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl or cyclooctyl radical.
The term xe2x80x9c(C1-C6)alkoxyxe2x80x9d is understood as meaning a group OR in which R is a (C1-C6)alkyl as defined above. A (C1-C6)alkoxy radical is for example a methoxy, ethoxy, propoxy, isopropoxy, butoxy, isobutoxy, tert-butoxy, n-pentyloxy or isopentyloxy radical.
The term xe2x80x9cacylxe2x80x9d is understood as meaning a group 
in which Rxe2x80x2 is hydrogen or a (C1-C6)alkyl as defined above.
Compounds of formula (I) form acid addition salts, for example with inorganic acids such as hydrochloric acid, hydrobromic acid, sulfuric acid, nitric acid, phosphoric acid and the like or with organic carboxylic acids such as acetic acid, propionic acid, glycolic acid, pyruvic acid, oxalic acid, malic acid, fumaric acid, tartaric acid, citric acid, benzoic acid, cinnamic acid, mandelic acid, methanesulfonic acid and the like.
Preferred compounds of formula (I) are those wherein:
n is 0 or 1;
R1 and R2 are each independently hydrogen or (C1-C6)alkyl;
R3 is cyano or trifluoromethyl;
R4 is hydrogen, (C1-6)alkyl, halogen, cyano, (C1-C6)alkoxy, trifluoromethyl, (C1-C6)alkylthio, (C1-C6)alkylsulfonyl or (C1-C6)alkoxycarbonyl;
R5 is hydrogen, halogen, (C1-C6)alkoxy or trifluoromethyl;
R6 is hydrogen;
or R3 and R6 together with the phenyl ring form a N-methylbenzotriazole.
Also preferred are the compounds of formula (I) wherein:
n is 0 or 1;
R1, R2 and R6 are each hydrogen;
R4 is halogen, cyano or trifluoromethyl.
Especially preferred compounds of formula (I) are those wherein R3 is cyano; those wherein R5 is hydrogen or trifluoromethyl; and those wherein n is 1.
Valuable compounds are selected from the group consisting of:
4-[N-(1H-imidazol-1-yl)-N-(4-trifluoromethylphenylmethyl)amino]benzonitrile
4-[N-(1H-imidazol-1-yl)-N-(4-chlorophenylmethyl)amino]benzonitrile,
4-[N-(1H-imidazol-1-yl)-N-(4-cyanophenylmethyl)amino]benzonitrile,
4,4xe2x80x2-[N-(1H-imidazol-1-yl)amino]bis-benzonitrile,
4-[N-(1H-imidazol-1-yl)-N-(4-fluorophenylmethyl)amino]benzonitrile,
4-[N-(1H-imidazol-1-yl)-N-(3,4-difluorophenylmethyl)amino]benzonitrile, and the acid addition salts, solvates or stereoisomeric forms thereof.
By virtue of their capability to inhibit aromatase, and thus to exhaust all sources of endogenous estrogens, the compounds of the present invention can be used alone or in combination with other active ingredients for the treatment or the prevention of any estrogen-dependent disorder or for the management of estrogen-regulated reproductive functions, in humans as well as in wild or domestic animals.
The breasts being sensitive targets of estrogen-stimulated proliferation and/or differentiation, inhibitors of aromatase are especially useful in the treatment or prevention of benign breast diseases in women, gynecomastia in men and in benign or malignant breast tumors with or without metastasis both in men and women (Brodie A M and Njar V C, Steroids, 2000, 65: 171-179; Pritchard K I, Cancer, 2000, 85, suppl 12: 3065-3072), or in male or female domestic animals.
Due to the involvement of estrogens in the mechanisms of ovulation, implantation and pregnancy, inhibitors of aromatase according to the invention can be used, respectively, for contraceptive, contragestive or abortive purposes in women (Njar V C and Brodie A M, Drugs, 1999, 58: 233-255) as well as in females of wild or domestic animal species.
The uterus is another reproductive organ responsive to estrogenic stimulation and inhibition of aromatase is therefore useful to treat or prevent endometriosis, benign uterine diseases or benign or malignant uterine tumors with or without metastasis in women (Njar V C and Brodie A M, Drugs, 1999, 58: 233-255) or in female domestic animals.
The ovary being the physiological source of estrogen, inhibitors of aromatase can be used to treat abnormal or untimely ovarian estrogen production such as polycystic ovary syndrome or precocious puberty, respectively (Bulun et al., J Steroid Biochem Mol Biol, 1997, 61: 133-139). Ovarian as well as non-ovarian but estrogen-producing benign or malignant tumors with or without metastasis (Sasano H and Harada N, Endocrine Reviews, 1998, 19: 593-607) may also benefit from treatment with aromatase inhibitors according to the invention.
In males, prostate and testicular tissues are also responsive to estrogenic stimulation (Abney T O, Steroids, 1999, 64: 610-617; Carreau S et al., Int J Androl, 1999, 22: 133-138). Therefore, aromatase inhibitors can be used to treat or to prevent benign (Sciarra F and Toscano V, Archiv Androl, 2000, 44: 213-220) or malignant prostate tumors with or without metastasis (Auclerc G et al., Oncologist, 2000, 5: 36-44) or to treat, prevent or control spermatogenesis functions or malfunctions, in men as well as in male wild or domestic animals.
Estrogens are also known to be implicated in the regulation of bone turnover; therefore, aromatase inhibitors may be useful, alone or in combination with other antiresorbtive or proosteogenic agents, in the treatment or prevention of bone disorders according to appropriate therapeutic sequences or regimens.
In addition, estrogens are involved in the regulation of the balance between Th1 and Th2 predominant immune functions and may therefore be useful in the treatment or prevention of gender-dependent auto-immune diseases such as lupus, multiple sclerosis, rheumatoid arthritis and the like.
When the compounds of formula (I) are administered for the treatment or prevention of estrogen-dependent disorders, they can be combined with one or several other sexual endocrine therapeutic agents. In the case of the control or management of reproductive functions such as male or female fertility, pregnancy, abortion or delivery, the compounds of formula (I) can be combined with for example a LH-RH agonist or antagonist, an estroprogestative contraceptive, a progestin, an anti-progestin or a prostaglandin. When the compounds of formula (I) are intended for the treatment or prevention of benign or malignant diseases of the breast, the uterus or the ovary, they can be combined with e.g. an anti-estrogen, a progestin or a LH-RH agonist or antagonist. In the case of the treatment or prevention of benign or malignant diseases of the prostate or the testis, the compounds of formula (I) can be combined with for example an antiandrogen, a progestin, a lyase inhibitor or a LH-RH agonist or antagonist.
The term xe2x80x9ccombinedxe2x80x9d refers herein to any protocol for co-administration of a compound of formula (I) and one or more other pharmaceutical substances, irrespective of the nature of the time of administration and the variation of dose over time of any of the substances. The co-administration can for example be parallel or sequential.
The invention thus also relates to a method of treating or preventing the above-mentioned diseases, comprising the administration to a subject in need thereof of a therapeutically effective amount of a compound of formula (I) or a pharmaceutically acceptable acid addition salt thereof, optionally in combination with another active ingredient.
For the treatment/prevention of any of these diseases, the compounds of formula (I) may be administered, for example, orally, topically, parenterally, in dosage unit formulations containing conventional non-toxic pharmaceutically acceptable carriers, adjuvants and vehicles. These dosage forms are given as examples, but other dosage forms may be developed by those skilled in the art of formulation, for the administration of the compounds of formula (I). The term parenteral as used herein includes subcutaneous injections, intravenous, intramuscular, intrastemal injection or infusion techniques. In addition to the treatment of humans, the compounds of the invention are effective in the treatment of warm-blooded animals such as mice, rats, horses, cattle sheep, dogs, cats, etc.
The pharmaceutical compositions containing the active ingredient may be in a form suitable for oral use, for example, as tablets, troches, lozenges, aqueous or oily suspensions, dispersible powders or granules, emulsions, hard or soft capsules, or syrups or elixirs. Compositions intended for oral use may be prepared according to any method known to the art for the manufacture of pharmaceutical compositions and such compositions may contain one or more agents selected from the group consisting of sweetening agents, flavoring agents, coloring agents and preserving agents in order to provide pharmaceutically elegant and palatable preparations. Tablets contain the active ingredient in admixture with non-toxic pharmaceutically acceptable excipients which are suitable for the manufacture of tablets. These excipients may be for example, inert diluents, such as calcium carbonate, sodium carbonate, lactose, calcium phosphate or sodium phosphate; granulating and disintegrating agents, for example, corn starch, or alginic acid; binding agents, for example starch, gelatin or acacia, and lubricating agents, for example, magnesium stearate, stearic acid or talc. The tablets may be uncoated or they may be coated by known techniques to delay disintegration and absorption in the gastrointestinal tract and thereby provide a sustained action over a longer period. For example, a time delay material such as glyceryl monostearate or glyceryl distearate may be employed.
They may also be coated by the technique described in U.S. Pat. Nos. 4,256,108; 4,166,452 and 4,265,874 to form osmotic therapeutic tablets for controlled release.
Formulations for oral use may also be presented as hard gelatin capsules wherein the active ingredient is mixed with an inert solid diluent, for example, calcium carbonate, calcium phosphate, or kaolin, or as soft gelatin capsules wherein the active ingredient is mixed with water or an oil medium, for example peanut oil, liquid paraffin, or olive oil.
Aqueous suspensions contain the active ingredient in admixture with excipients suitable for the manufacture of aqueous suspensions. Such excipients are suspending agents, for example sodium carboxymethylcellulose, methylcellulose, hydroxypropylmethylcellulose, sodium alginate, polyvinylpyrrolidone, gum tragacanth and gum acacia; dispersing or wetting agents, for example a naturally-occurring phosphatide, such as lecithin, or condensation products of an alkylene oxide with fatty acids, for example polyoxyethylene stearate, or condensation products of ethylene oxide with long chain aliphatic alcohols, for example heptadecaethyleneoxycetanol, or condensation products of ethylene oxide with partial esters derived from fatty acids and a hexitol such as polyoxyethylene sorbitol monooleate, or condensation products of ethylene oxide with partial esters derived from fatty acids and hexitol anhydrides, for example polyethylene sorbitan monooleate. The aqueous suspensions may also contain one or more preservatives, for example ethyl, or n-propyl, p-hydroxybenzoate, one or more coloring agents, one or more flavoring agents, and one or more sweetening agents, such as sucrose, saccharin or aspartame.
Oily suspensions may be formulated by suspending the active ingredient in a vegetable oil, for example arachis oil, olive oil, sesame oil or coconut oil, or in mineral oil such as liquid paraffin. The oily suspensions may contain a thickening agent, for example beeswax, hard paraffin or cetyl alcohol. Sweetening agents such as those set forth above, and flavoring agents may be added to provide a palatable oral preparation. These compositions may be preserved by the addition of an anti-oxidant such as ascorbic acid.
Dispersible powders and granules suitable for preparation of an aqueous suspension by the addition of water provide the active ingredient in admixture with a dispersing or wetting agent, suspending agent and one or more preservatives. Suitable dispersing or wetting agents and suspending agents are exemplified by those already mentioned above. Additional excipients, for example sweetening, flavoring and coloring agents, may also be present. The pharmaceutical compositions of the invention may also be in the form of an oil-in-water emulsions. The oily phase may be a vegetable oil, for example olive oil or arachis oil, or a mineral oil, for example liquid paraffin or mixtures of these. Suitable emulsifying agents may be naturally-occuring phosphatides, for example soy bean, lecithin, and esters or partial esters derived from fatty acids and hexitol anhydrides, for example sorbitan monooleate, and condensation products of the said partial esters with ethylene oxide, for example polyoxyethylene sorbitan monooleate. The emulsions may also contain sweetening and flavouring agents.
The pharmaceutical compositions may be in the form of a sterile injectable aqueous or oleagenous suspension. This suspension may be formulated according to the known art using those suitable dispersing or wetting agents and suspending agents which have been mentioned above. The sterile injectable preparation may also be a sterile injectable solution or suspension in a non-toxic parenterally-acceptable diluent or solvent, for example as a solution in 1,3-butanediol. Among the acceptable vehicles and solvents that may be employed are water, Ringer""s solution and isotonic sodium chloride solution. In addition, sterile, fixed oils are conventionally employed as a solvent or suspending medium. For this purpose any bland fixed oil may be employed including synthetic mono- or diglycerides. In addition, fatty acids such as oleic acid find use in the preparation of injectables.
Dosage levels of the order of from about 0.0001 mg to about 1 mg/kg of body weight per day are useful in the treatment of the above-indicated conditions, or alternatively about 0.1 mg to about 10 mg per patient per day.
The amount of active ingredient that may be combined with the carrier materials to produce a single dosage form will vary depending upon the host treated and the particular mode of administration. Dosage unit forms will generally contain between from about 1 mg to about 100 mg of active ingredient, typically 2 mg, 5 mg, 10 mg, 20 mg, 40 mg, 50 mg, 60 mg, 80 mg, or 100 mg.
It will be understood, however, that the specific dose level for any particular patient will depend upon a variety of factors including the age, body weight, general health, sex, diet, time of administration, route of administration, rate of excretion, drug combination and the severity of the particular disease undergoing therapy.
The 1-N-phenyl-amino-1H-imidazole derivatives of formula (I) of the invention and their acid addition salts can be prepared following the general scheme 1. 
According to scheme 1 aniline derivative (1) is condensed with the aldehyde of formula (2) and the imine intermediate is reduced with sodium borohydride or hydrogenated using palladium or platinium oxide as catalyst to afford the N,N-disubstituted aniline (3). Said aniline (3) can also be prepared by reaction of a halogeno derivative (8) with an aniline of formula (1).
The N,N-disubstituted aniline (3) is converted to its nibroso derivative using standard conditions, then reduced to afford the 1,1-disubstituted hydrazine of formula (4).
Alternatively, the 1,1-disubstituted hydrazine (4) can be prepared by selective N-alkylation of a compound of formula (7) with a compound of formula (8) using the conditions described by U. LERCH and I. Kxc3x96NIG (Synthesis, 1983, 2, 157-8).
Then, condensation of (4) with dialkyloxy-alkyl-isothiocyanate derivatives or ethylenedioxy-alkyl-isocyanate derivatives, affords the thiosemicarbazide (5) which is transformed to the 1-amino-imidazole-2-thione (6) by treatment with an acid like acetic acid or sulphuric acid.
Desulfurization of (6) in acetic acid, following the conditions described by S.GRIVAS and E.RONNE in Acta Chemica Scandinavia, 1995, 49, 225-229, gives the final 1-N-phenylamino-1H-imidazole derivative (I), which is optionally converted to one of its pharmaceutically acceptable acid addition salts. Alternatively compound (I) where R3 or R6 is an electron-withdrawing group can be obtained by condensation of the N-imidazoloaniline (9) with the halogeno derivative (8).